Geology of the Chang'e-5 landing site: Constraints on the sources of samples returned from a young nearside mare

Abstract

Extraterrestrial materials collected by sample return exploration missions have advanced our understanding of planetary formation and evolution in a profound manner. This is achieved through sophisticated laboratory sample analyses with very high precision and accuracy that are difficult to obtained by orbital or surface landing/roving explorations. Moreover, the well-known geographical location and geological context of returned samples enable the sample measurements to be fully interpreted and mapped into the entire planetary context (in contrast to meteorites where the geological context is missing). Planetary scientists have been endeavoring to collect and returned samples from extraterrestrial bodies, despite the significant costs involved.In December 2020, China's Chang'e-5 mission successfully landed in and returned lunar samples from the northeastern Oceanus Procellarum in the western lunar nearside maria. The mare basalt at the landing site has been dated to be ~1–2 Ga through crater population studies, much younger than any basalts in the present lunar sample collections and among the youngest maria on the global Moon (e.g., Hiesinger et al., 2011). The Chang'e-5 sample will provide an unprecedented opportunity to characterize the late-stage lunar volcanism.To fully explore the scientific potential of the Chang'e-5 returned samples and assist the on-going sample analyses and interpretations, we present an in-depth investigation of the geology of the specific Chang'e-5 landing site and the nearby vicinity using high-resolution remote sensing data sets. We characterize the detailed geological context, topography, morphology, morphometry, chemical and mineralogical composition of the local landing area. These geological characterizations lead us to identify a sequence of four geological events, including mare volcanism, tectonism, impact cratering and ejecta deposition, that have potentially affected and been recorded in the returned samples. Compositional and geochronological measurements of the Chang'e-5 samples would reconstruct a detailed regional geological evolution model of the landing area. Furthermore, most of the inferred ages of these geological events lie in the age gap of the Apollo/Luna samples. Precise determination of these ages through radiogenic isotope analyses would be invaluable in narrowing down the uncertainties of the lunar cratering chronology function and improve our understanding of the geological history of the entire Moon.